HoN was a good stopgap between Dota and Dota 2 - the engine was smooth and in the early days when they still worked with Icefrog the balance wasn't even too bad.
But I really think D2 outshines it in every way possible, mechanics, engine, art, balance, valve didn't sell my email to spammers, etc.
I like both Dota 2 and HoN, but HoN definitely has the upper hand with regards to fast-pace twitch-based gameplay. The first thing a HoN player notices when trying out Dota 2 for the first time is that input delay.
Supposedly part of the problem is that Dota 2 uses the Source engine with netcode designed for FPS games; hence it does prediction and interpolation which works well for those games but not as well for RTS games. For more info: http://pastebin.com/ekk07PKn
But I really think D2 outshines it in every way possible, mechanics, engine, art, balance, valve didn't sell my email to spammers, etc.